Dam and method of making same



- April 18,- 1933.

J. B. GIRAND DAM AND METHOD OF MAKING SAME 3 Sheets-Shea 1 Filed Feb- 25. 1931 INVENTOR (11?. Gfira ml,

ATTORNEY WITNESSES Q if A ril 18, 1.933. J. B. GIRAND 1,903,760 DAM ANDHETHOD OF MAKING SAME J Filed Feb 25 1931 5 Sheets-Sheet 2 INVENTOR WITNESSES ,5, (it rand, 5 H

ATTORNEY p i I, J. B. GIRAND 1,903,760

DAM AND METHOD OF MAKING SAME Filed Feb. 25, 1931 3 Sheets-Sheet 3 INYENTOR c133. @a/ramd ATTORNEY Patented Apr. 18, 1933 PATENT OFFICE JAMES GBAND, OF PEOENIX, ABIZONA DAM A231) EFEHOD 0F Application filed February 25,1931. Serial l'iTo. 518,230.

This invention relates to improvements in dams, and it consists of the constructions, combinations, arrangements and method herein described and claimed.

An object of the invention is to build e rock-fill dam along such lines that earthquakes and other causes of internal disturbones will not he able to flatten it and genorally do no more harm than interrupt the 0 otherwise face of the water 'tigst morn crane with a shallow concavity.

Another object of ihe invention is to provide for roclr-iiil'dams a flexible Waterproof diaphragm on the upstream side, this being hacked by a mobile stratum which has the special quality of so disseminating any local relaxation either in its own structure or in 'is rock hase thai; ho; ho slightest depres sion will occur in said diaphragm by virtue of DES flexibility, and what depression over so wide an area iha; ii? will hardly he perceotihle end thai none of? the joints will he ruptured A fursher ohjeci: or the inven'sion is to introduce a thick or hlanlrei of sized washed and screened river gravel between the rock-fill of a dam of that type and the ultimate outer skin or concrete, Waterproof diaphragm.

A further object of the invention is building of auxiliary or secondary fills, par a llcl to the main fili yet apart from the main fill, so that the work of piecing she gravel facing or cushion, as Well as the concrete diaphragm, can proceed at the same time that the main ill is heing formed.

Other ohjecis and advantages will appear in the following specification, reference losing had "so the accompanying drawings in which Figure 1 is a vertical seciion of a portion of a rock-fill dam embodying "the principles or the invention.

Figure 2 is a sectioned diagram illustrasing the method of making the dam wherehy the ultimaie water right membrane occupies an angle considerably flatter .than the angle of repose ordinarily assumed by dumped rock, gravel or the like.

Figure 3 is a detailsectionai view illustrab ing some of the details of the flexible diaphragm, especially the mode of anchoring the water tight membrane to its foundation slab.-

Fignre 41 is a similar sectional view illustraeing the details of the footing.

Figure 5 is a sectional perspective view of a portion oi the flexible diaphragm, showing how she water tighfinieinhrane is superimposed on its foundation slob.

Figure 6 is a deiaii sectionai view paribicniarly showing one of the Warez stops.

Figure 7 is a sectional view of a canyon showing how she ends end holzioro off the dam are embodied in the rock Walls. 4

Figure 8 is a cross section taken on the line 8-8 of Figure 5., showing in deisii howone end oi the am is embedded in the ad jacent rock Wall.

The oustending feature 0? the invention resides in What is herein km! Wn as a flexible diaphragm generally denote 1 (Figs. fl and 3). This diaphragm involves niech icai details of construction which are fuhy scrihed later, and it is for the purpose of malring clear how the integrity of this diaphragm is intended to he preserved in practice, the method of construction of the rock base and its constituents is described first.

is a natural fact (that rocks dumped on a pile will {all over 31/311 other onbil ihey come to rest at an angle of repose which is about 1.4 to i, or in. other Words, 1.4 feet of base dimension for every foot of altitude. An internal disturbance in the rock pile of any serious-proportions is likely to upset the 7 balance of this nainrol angle of repose so ihat some she rocks are either loosened and sent tumbling down the sides or are caused to fell into a hole in case the disturha'nc'e causes an internal sinking.

Where this is irue of an ordinary rock pile it is eqnaiiy true of a rock-fill dam only here the consequences are likely to be disastrous ii an impounded volume of Water depends upon the dam "for its retention. Therefore, one'of the first purposes is to so flatten our the face of she dam that it will not he possible for any ordinary earthquake to fiatiien it further. I This is accomplished lay producing 1. intended to emphasize how it is a 1.6 to 1 ratio, in other words approximately 11:1 foot base dimension for every foot altitu e.

At this point it must be explained that this ratio is not conclusive. The 1.6 to 1 ratio is merely cited for illustration, and is intended to show one example of base extension beyond that which would be found if the material were permitted to assume an angle of repose of its own accord.

Reference is made to the drawings. A rock base shown at 2 (Figs. 1 and 2) comprises a mainrock-fill 3 and a plurality of auxiliary fills 4, 5, 6, 7, etc. (Fig. 2). In order to flatten the face of the rock base 2, in other words, to lessen the steepness of the natural angle of re ose 8 (Fig. 2), the succeeding fills 4, 5, 6, etc., are dumped upon each other but are so proportioned that their widths along the lines 9 are progressively less toward the top of the dam.

As a result of this construction, the face 10 of the rock base (Fig. 2) will be flatter, so to s eak, than the natural angle of repose 8. t is perfectly plain that if even a flatter face 10 were desired, the only requirement would be to dump more rock in the fill 4 in order to extend it out farther from the main rock fill 3, and then dum the succeeding auxiliary fills 5 in proportionate volumes.

In this way the face 10 can be made as flat as desired, and rather than adhere to the 1.6 to 1 ratio the proportion arrived at might be 1.8 to 1, 2 to 1, etc. The auxiliary fills 4, 5, etc., are made in lifts that are most convenient, but in the case of the dam under consideration was regarded as feet high.

It is to be noted that in dumping these auxiliary fills the face slopes are bound to assume the natural angle of repose 1.4 to 1. The inclined faces of the succeeding fills are, therefore, parallel to the face 8 of the: main rock-fill 3. The so-called flattening of the face 10 (Fig. 2) is not produced by disturbing the material in the fills 4, 5, etc., in any way but by successively diminishing the volume of these from bottom to top of the dam, so that a. meanface line 11 (Fig. 2) will stand at a lesser angle than the angle of the face 8.

The immediately preceding description is possible to produce a face 10 (Fig. 2) flatter than the natural le of repose of the face 8. 'It is not a spec c requirement that the rock fill 3 be completed in its entirety before .the auxiliary fills 4, 5, etc. are begun. The plan would be to carry the main rock fill- 3 to snappropriate altitude, say feet, andthen begin the auxiliary fill 4. All that needs be known is the base dimension of theauxiliary fill 4 V as well as those of the succeeding auxiliary fills, and when these are made progressively smaller the mean face linell will be found unimpaired in the completed rock hast 2.

This mode of construction interrupts the face 10 (Fig. 2) with a succesion of set-backs 12.

ese appear small on the drawing, but in practice they are wide enough to support a spur track which will be extended across the canyon 13 (Fig. 7) as the auxiliary fill progresses- A gravel facing 14 (Figs. 1 and 2) is dumped upon the face 10. This gravel facing comprises a large body of sized, washed and screened river gravel between the mam dumped rock-fill 3 and a concrete, watertight diaphragm referred to later. This gravel facing or bed is not fine material. It is composed of stones from 1 to 3 inches in diameter; absolutely free from dirt, sand or fine pieces. As previously stated, it is sized in order that it may quickly readjust itself in case of settlement, which it would not do if fines of any kind were used in the gravel blanket. The gravel facing thus constitutes a mobile stratum which has the propert of flowing into any settlement in the rock ase 2 and so distribute the de ression over an extremely wide area in 0 er to avoid any sudden drop or break in the flexible diaphragm 1 which is laid" directly on the gravel facing 14 as shown. The gravel facing constitutes the immediate support of the flexible diaphragm 1, the resultin dam con-v struction diflermg from (Erevai ing practices in which the ultimate 'aphragm is laid directly on the rock hence is at the mercy of any internal istrubance which will unsettle the position of the rocks.

The merit of the gravel-facing 14 is better explained as follows :'Assume that from an earthquake or some other cause, the rocks in the base 2 have settled as indicated at 15 (Fig. 1), producing what would appear as a large depression 16. This depression is communicated to the gravel facing 14 which immediatelyflows into the depression 16 from all sides and above over a wide area adjacent to the flexible diaphragm 1. i

It can easily be seen that instead of a dro of the approximate distance 17 (Fig. 1) ing communicated to the flexible diaphragm 1 the maximum amount of drop of the diaphragm would scarcel be noticeable, and if detected at all wo d appear as a large shallow depression represented by the easy lowering over a very wide area of the diaphragm into the shallow concavity in the gravel facing 14. V v

- It is thus the purpose of the gravel facing 14 to distribute any settlement in the mo base 2 over a lar sugrficial area. The diaphragm 1 will t us ow but a slight lower- 1n over a wide area, and will not su'fler a su den dro and co uent breakage immediately a va where flue basic as ement 15 occurred.

The angle of repose 18 of the 'gravel facing 14 is substantially parallel to 0 mean face line 11 (Fig. 2) of the auxiliary fills 4, 5, etc. This angle of repose 18 is obtained by raking because simply dumping would not do. Again, the gravel facing is not applied in its entirety at. the beginning,but is built up as the construction of the dam progresses. This is equally true of the flexible diaphragm 1, and the construction of this is as follows 1- An asphaltic solution 19 is sprayed on or otherwise applied to the surface of the gravel facing 14. Its purpose is to prevent the fines of the concrete mix from passing into the gravel fill. The flexible diaphragm 1 comprises a foundation slab 20 and a water tight membrane 21. The slab is laid on the impervious asphaltic skin or covering 19. It

1 comprises succeeding courses of large blocks (Fig. 5) of any suitable dimension, but in 'plete shrinkage of the blocks 22,

this case are regarded as 16 feet square in top surface area.

They will be laid in alternation across the canyon. To give an illustration, the blocks 22, 24, etc. (Fig. 5) would be laid (1n the third course for'example) and permitted to set, whereupon blocks 23, etc. would belaid in the spaces between. This enables com- 24, etc. before the intervening blocks are laced.

In la ing the fourth course, t e same plan would he followed. All of the blocks are laid in horizontal courses across the canyon 13 (Fi 7) in alternation,'the spaces between bloc s bein filled later to complete a given course. A r the foundation slab is completed, the outer surface is coated w th a thin washof asphalt 20 (Fig. 3).

It has been stated that the auxiliary fill 4 is begun after the main rock-fill has been carried to only a part of its ultimate height. This partially explains an advantageous structural rinciple 'accordingto which the finishing'oi the damcan be proceeded with while the dumping of the rock-fill s yet in progress. y p

The process here involved s to carry the main rock-fill to a certain height, as explained, apply the auxiliary fill 4, next apply the the slab 20. t5

avel cushion to-the requisite depth and fina y apply the concrete diaphragm. These various steps of the work can be carried out at virtually the same time so that there need not be great delays between any of the stages of construction.

Reinforcing material 25 (Fig. 5) is incororated in the courses of blocks. The .reinorcing rods run in both directions through the centers of the blocks. Every third block in the succeeding higher course is equippedwith a rib 26 (Fig.5). These ribs are staggered in position. They are sunkinto the gravel facin 14 and tend to prevent any slidmg of the exible diaphragm 1 that might occur especially'among the lower blocks of Inasmuch as the pressure of water, is

greater at the bottom of the dam than at the top the slab 20 is made thickest at the bottom, and the thickness is graduated to a predetermined minimum dimension at the .top as suggested in Figure 1.- The thickness of succeeding courses of slab blocks is easily regulated during the construction of the dam.

Considerable importance is attached to the connection of the toe or bottom of the dam with bed rock. This is accomplished by digging a trench 27 (Figs. 1, 2 and l) and filling this with concrete 28. This concrete fill becomes an abutment on which the water proof diaphragm has a footing. In placing this concrete fill the use of a suitable form produces the contour 29 which comprises a succession of rectangular recesses or steps on which the first course of blocks of the slab 20. rests. I

This bourse is difierent'from the rest, hence is designated 30 (Figs. 1, 2 and 4:) for distinction. The blocks in this course comprise concretelaminations 31. Each layer isla'id separately and in alternation in the exact manner previously described for the third and succeeding courses (Fig. 5). The blocks in the various layers are so laid as to stagger'or break the joints 32 (Fig. 4). A thin wash or spray of asphalt 33 is applied to the layers as. completed.

Reinforcing rods, originally set in the concrete fill 28 .(Fig. 4') are later incorporated in the various layers of the colirse 33 as these are completed. The result of this construetion is a laminated course rigidly connected to the fill 28 but projecting upwardly beyond the spur 35 thereof to the following ad- I vantage :It is expected that some cracks will develop in the laminations of the bottom course 30. This'is likely because of the enormous weight concentrated on the foot- .ingof the dam. The possibility of'crackmembrane 21, this because of the elasticity of the blocks and because of the asphaltic separation which has a sealing quality of its own.

the footing or bottom of the dam Fig. 4) is carried out along the ends of (Fig. 7). The'rigidside walls'of the canyon 13 are channeled at 36 (Fig. 8) to enable extend- A principle identical to that emploved in ing. the end courses of blocks thereinto and sealing them with concrete or other suitable fills 37. The channels 36 will he in continuation of the trench 27. and the fill 37.

although later emplaced, will be a virtual extension of the concrete fill 28.

The water tight membrane 21 is composed of blocks of concrete cast alternately in horizontal courses, but may be thinner than the blocks of foundation slab 20 therebeneath. The'blocks of the membrane 21 are reinforced in both directions (Fig. 5) as at 38. They are so laid that the superimposed joints willbe broken. However, the crossing of joints cannot be prevented, and where this occurs copper water stops 39 are so placed ated in thickness from base to crest, as are the blocks in the foundation slab, they are of equal thickness throughout. In order to make the membrane 21 water tight the joints 42 (Fig.6) in the blocks will be filled with a mixture of asbestos and asphalt in such proportions that when tamped with an appropriate hammer the asphalt willjust be flush with the surface.

Anchors 43 are embedded in the slab 20, later to be bent over at 44 (Fig. 3) so as to be confined within the blocks of the membrane 21. These anchors may take any preferred shape. Their purpose is to keep the blocks of the membrane 21 centered upon the foundation slab 20. However, these blocks are capable of some expansion and contraction in reference to the anchors 43, imparting to the diaphragm 1 that degree of flexibility necessary to its functioning as already outlined.

In addition to the foregoing construction the invention also resides in the method of making the dam. The outstanding steps of this are as follows :First the production of the mean face line 11 (Fig. 2) at-a lesser angle than the natural angle of repose 8 assumed by the rock in dumping. The arrival at the mean face 11 requires a building up of the face of the rock fill 8 by a succession of auxiliary fills 4, 5, etc.

The next step resides in the application of the mobile cushion 14 which has the quality of disseminating any internal relaxation of the rock base 2. The gravel will flow into the depression 16 from all sides and so have the effect of extending the depression over a widearea, but in doing so to so lessen the depression that its effect on the diaphragm 1 will hardly be noticed.

Next to this is the step of building up the flexible diaphragm 1. This comprises the foundation slab 20 and the watertight membrane. The joints between the blocks in this membrane are made water tight by the asbestos asphalt joint compound.

I claim 1. A dam comprising a'rock fill base, a water tight diaphragm spaced from the face of the rock fill base, and an inte sed mobile stratum of loose, free-moving e ements resting on the rock fill base and supporting the diaphragm being capable of flowing into a depression 1n the rock fill base and thus maintaining the support of the dia hragm.

2. A dam comprising a roc fill base, a watertight diaphragm spaced from saidbase and consisting of a plurality of blocks with means for connecting them to render the diaphragm flexible, and a stratum of gravel interposed between the rock fill base and diaphragm resting on said base.

3. A dam comprising a rock fill base, a flexible watertight covering diaphragm, and a fluent gravel stratum means between the base and diaphragm, yielding to a relaxation of the rock fill base but disseminating the resulting depression over a wide area beneath the diaphragm.

4. A dam comprising a rock fill base having a mean face line of a lesser inclination than the natural angle of rock-repose, a'covering watertight diaphragm spaced from said 5. A dam comprising a rock fill base, a

gravel facing on the rock fill base, a water proof diaphragm applied to the gravel facing, and ribs projecting from the diaphragm into the gravel facing.

6. A dam comprising a rock fill base, an abutment adjacent to the base said abutment including a spur. a gravel facing on the rock fill base confrontingand contacting the spur, and a water proof diaphragm covering the gravel facing and having its footing on the abutment.

7. A dam comprising a rock fill base, an

abutment adjacent to the rock fill base, said abutment having a stepped contour and a spur, a gravel facing applied to the rock fill base and contacting the spur, a water proof diaphragm laid on the gravel facing, and a bottom course included in said diaphragm being composed of laminations having footings on the stepped contour of the abutment.

8. In a dam, a base having a face with a plurality of set backs from bottom to crest, a mobile gravel facing applied to the face and resting in part on the set backs to prevent any tendency toward rolling down and piling up at the bottom, and a water proof diaphragm covering the gravel facing.

9. In a dam. a base having an inclined face, a gravel facing applied to said face, an adjacent abutment having a spur with which a part of the facing contacts. reinforcing rods embedded in the abutment and extending over both the spur and a part of a facing,

. of the cushion until substantially parallel impasse a water proof diaphragm laid on the facing,

and a bottom conneincluded in the dia phragm, consistinginof laminations formed around said exten g reinforcing rods and havin chief support upon said spur.

10; he herein described method consisting of making a base by dumping rocks to term a succession of set backsand produce a mean face line of a lesser inclination than the angle of repose of the rocks, dumping a gravel cushion on said set backs and raking the face with said mean face line, coating the cushion with an impervious skin, and 'huilr g a water proof diaphragmin stages over said skin.

11. The herein described method consisting of dumping'a main rock-fill to only a portion of its ultimateheight, dumping an auxiliary fill at the base of the main rook-fiii preparatory to disposin the face of the dam.

at an inclination less t an the angle of repose of the main rock-fill, applying a gravel V facing to the auxiliary fill, constructm a water-proof diaphragm on' the gravel facm g,-

and continuing the foregoing operations m progressive order toward the top of thedam until the latter is completed.

1 12. A dam comprising a rockfifl base, a layer of gravel covering the u stream face of the base, and a water-proo diaphragm supported by said g'ravel layer.

w AMES' B. omimn. 

